St. John of God is a Catholic saint and the founder of the Brothers Hospitallers of Saint John of God, a religious organization active in more than 300 hospitals worldwide dedicated to caring for the sick, the poor and those afflicted with mental disabilities. Saint John lived in Portugal and Spain in the early to mid 1500s. He is considered one of Spain's most important religious figures and has a personal feast day that is celebrated on March 8.
Saint John of God was, at various times in his life, a soldier in the Holy Roman Empire's army, a sheep farmer in Spain and Portugal, a missionary in Africa and an occupant of a mental hospital in Spain. It is believed that he experienced a religious conversion after hearing a sermon given by John of Avila on Saint Sebastian's Day around 1535.
Saint John of God's birth name was João Duarte Cidade, and this is the name that he used until after his 40th birthday. Even though Saint John lived almost 500 years ago, a wealth of information exists about his life thanks to several biographies that were written about him shortly after his death. The most famous of these was written by Francisco de Castro and later translated into Italian by Giovanni Bordini.